Different types of push-in fasteners are known for use in different environments and for different purposes. A basic design for a push-in fastener includes a body that is inserted into aligned openings in first and second articles, or into an opening in at least one of the articles. The fastener body includes a collar or head larger than the opening or openings in the article or articles, and deflectable portions or legs that yield as the body is inserted through the openings and rebound when fully through the openings. The legs are bowed outwardly to define a maximum diameter larger than opening(s) in which the fastener is inserted. During installation of the fastener, the legs deflect inwardly so as to pass through the opening and then rebound outwardly as the maximum diameter portion passes through the opening. The articles to be secured by the fastener can be sandwiched between the collar and the rebounded deflectable portions of the body. A pin of the fastener is inserted into and retained by the body after the body is seated in place in the articles. The pin wedges against the deflectable portions of the body to secure the body in place, and may include still further deflectable elements to increase the retention force of the fastener.
In some known push-in fasteners the body and pin are independent components, completely separate from one another before installation. In other known push-in fasteners, the body and pin having a preinstalled position in which the pin is held in the body but does not interfere with installation of the body in a work piece. The body is first inserted and seated in place by pushing on the head of the body. Once the body is fully seated, the head of the pin is pushed until the pin too is fully seated in the body. It is known to provide the head of the body and the head of the pin of substantially the same size. It is also known in some applications to provide the fastener in a channel or in a shallow well or cavity to conceal and/or protect the heads of the body and the pin.
Deficiencies of known designs for this purpose include the inability of the pin to stay in a pre-drive position until the body is firmly seated. If the pin of the fastener falls from the body of the fastener, the advantages of preassembling fastener are lost. When assembling the articles and fastener, if the pin of the fastener is moved axially inward too far relative to the body of the fastener before the body is firmly seated in the article receiving the body, the pin and body can become locked without the body being seated properly. The articles to be secured by the fastener are not held firmly against one another if the body is not fully inserted and seated where intended. The inability of the pin to stay in the pre-drive position can be improved by increasing the drive interference between the pin and the body; however, this can make the final connection achieved by driving the pin into the body more difficult. Generally, it is desirable that the fastener drives easily but is retained securely. Accordingly, it is often necessary to drive the body by pushing only against the collar of the body and not against the head of the pin. This can be awkward in many assembly situations in which the collar of the body is partly concealed by the head of the pin. Many known fastener designs do not disassemble easily, and are not reusable. This can be problematic if the fastener is used in an assembly that may require periodic disassembly. Further, disassembly can result in damage, or complete separation of the fastener components, making reuse inconvenient or impossible.
It is known also to provide a head on the pin shaped for attachment to another component or thing to be held in position by the fastener. The body can be attached to one piece and the pin to another. By securing the pin and body together, the pieces separate attached to the body and pin are then held in position relative to one another.
Fasteners of these types have been used advantageously and are accepted in many applications. However, such fasteners are not without inadequacies and deficiencies for some uses and applications. Accordingly, push-in fasteners having different characteristics and features are needed.